This invention relates to a welding torch and more particularly to a torch, which fits over a tube to weld the tube to the back side of a tubesheet.
The manufacturer of liquid metal heat exchangers for the production of electricity from nuclear energy presently contemplates the utilization of double wall tubes in the heat exchanger to transfer heat from a liquid metal to water or steam. To provide leak detection in either wall of the heat exchanger tube, the tubes will be welded to both the front and back side of the tubesheet. Apparatus for welding the tubes to the front side of the tubesheet is in current use, however, welding on the back side of the tubesheet is more difficult because of the interference of the tubes and the limited space between the tubes. Local manual repair of weld defects in this area is the most difficult operation for which no welding torch is presently available.